Re: [RFC PATCH 00/56] Dynamic mitigations

Josh Poimboeuf
2025-10-15T15:43:10Z

On Wed, Oct 15, 2025 at 01:53:31PM +0000, Kaplan, David wrote:
> > If `root` is capable of setting `mitigations=off` via this interface,
> > doesn't that somewhat defeat the purpose of denying `/proc/kcore`
> > access in lockdown confidentiality mode? Assuming one is running on a
> > CPU with some form of side-channel memory read vulnerability (which they
> > very likely are), they can turn off all mitigations, then read kernel
> > memory via one of those exploits.
> >
> > There should be a one-way switch to allow denying all further writes to
> > this interface, so that once the system's mitigations are set properly,
> > any further attempts to change them until the next reboot can be
> > prevented.
> >
>
> That's a good idea, there could be a separate mitigation_lock file
> perhaps that once written to 1 denies any further changes.

Wouldn't the enablement of lockdown mode effectively function as that
one way switch?

--
Josh